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tailscale/net/netstat/netstat_windows.go

180 lines
4.1 KiB
Go

// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package netstat returns the local machine's network connection table.
package netstat
import (
"errors"
"fmt"
"math/bits"
"syscall"
"unsafe"
"golang.org/x/sys/windows"
"inet.af/netaddr"
"tailscale.com/util/endian"
)
// See https://docs.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-getextendedtcptable
// TCP_TABLE_OWNER_PID_ALL means to include the PID info. The table type
// we get back from Windows depends on AF_INET vs AF_INET6:
// MIB_TCPTABLE_OWNER_PID for v4 or MIB_TCP6TABLE_OWNER_PID for v6.
const tcpTableOwnerPidAll = 5
var (
iphlpapi = syscall.NewLazyDLL("iphlpapi.dll")
getTCPTable = iphlpapi.NewProc("GetExtendedTcpTable")
// TODO: GetExtendedUdpTable also? if/when needed.
)
type _MIB_TCPROW_OWNER_PID struct {
state uint32
localAddr uint32
localPort uint32
remoteAddr uint32
remotePort uint32
pid uint32
}
type _MIB_TCP6ROW_OWNER_PID struct {
localAddr [16]byte
localScope uint32
localPort uint32
remoteAddr [16]byte
remoteScope uint32
remotePort uint32
state uint32
pid uint32
}
func get() (*Table, error) {
t := new(Table)
if err := t.addEntries(windows.AF_INET); err != nil {
return nil, fmt.Errorf("failed to get IPv4 entries: %w", err)
}
if err := t.addEntries(windows.AF_INET6); err != nil {
return nil, fmt.Errorf("failed to get IPv6 entries: %w", err)
}
return t, nil
}
func (t *Table) addEntries(fam int) error {
var size uint32
var addr unsafe.Pointer
var buf []byte
for {
err, _, _ := getTCPTable.Call(
uintptr(addr),
uintptr(unsafe.Pointer(&size)),
1, // sorted
uintptr(fam),
tcpTableOwnerPidAll,
0, // reserved; "must be zero"
)
if err == 0 {
break
}
if err == uintptr(syscall.ERROR_INSUFFICIENT_BUFFER) {
const maxSize = 10 << 20
if size > maxSize || size < 4 {
return fmt.Errorf("unreasonable kernel-reported size %d", size)
}
buf = make([]byte, size)
addr = unsafe.Pointer(&buf[0])
continue
}
return syscall.Errno(err)
}
if len(buf) < int(size) {
return errors.New("unexpected size growth from system call")
}
buf = buf[:size]
numEntries := endian.Native.Uint32(buf[:4])
buf = buf[4:]
var recSize int
switch fam {
case windows.AF_INET:
recSize = 6 * 4
case windows.AF_INET6:
recSize = 6*4 + 16*2
}
dataLen := numEntries * uint32(recSize)
if uint32(len(buf)) > dataLen {
buf = buf[:dataLen]
}
for len(buf) >= recSize {
switch fam {
case windows.AF_INET:
row := (*_MIB_TCPROW_OWNER_PID)(unsafe.Pointer(&buf[0]))
t.Entries = append(t.Entries, Entry{
Local: ipport4(row.localAddr, port(&row.localPort)),
Remote: ipport4(row.remoteAddr, port(&row.remotePort)),
Pid: int(row.pid),
State: state(row.state),
})
case windows.AF_INET6:
row := (*_MIB_TCP6ROW_OWNER_PID)(unsafe.Pointer(&buf[0]))
t.Entries = append(t.Entries, Entry{
Local: ipport6(row.localAddr, row.localScope, port(&row.localPort)),
Remote: ipport6(row.remoteAddr, row.remoteScope, port(&row.remotePort)),
Pid: int(row.pid),
State: state(row.state),
})
}
buf = buf[recSize:]
}
return nil
}
var states = []string{
"",
"CLOSED",
"LISTEN",
"SYN-SENT",
"SYN-RECEIVED",
"ESTABLISHED",
"FIN-WAIT-1",
"FIN-WAIT-2",
"CLOSE-WAIT",
"CLOSING",
"LAST-ACK",
"DELETE-TCB",
}
func state(v uint32) string {
if v < uint32(len(states)) {
return states[v]
}
return fmt.Sprintf("unknown-state-%d", v)
}
func ipport4(addr uint32, port uint16) netaddr.IPPort {
if !endian.Big {
addr = bits.ReverseBytes32(addr)
}
return netaddr.IPPortFrom(
netaddr.IPv4(byte(addr>>24), byte(addr>>16), byte(addr>>8), byte(addr)),
port)
}
func ipport6(addr [16]byte, scope uint32, port uint16) netaddr.IPPort {
ip := netaddr.IPFrom16(addr)
if scope != 0 {
// TODO: something better here?
ip = ip.WithZone(fmt.Sprint(scope))
}
return netaddr.IPPortFrom(ip, port)
}
func port(v *uint32) uint16 {
if !endian.Big {
return uint16(bits.ReverseBytes32(*v) >> 16)
}
return uint16(*v >> 16)
}